Cardiorespiratory arrest

Once cardiac or respiratory arrest has occurred, early ventilation is a priority. Expired air ventilation is best performed with the aid of a specially designed pocket mask. In this type of system the rescuer holds the mask tightly to the patient's face and, using thumbs and forefingers, lifts the angles of the jaw to open the airway and blows into the inspiratory port. A unidirectional valve allows the patient's expired air to vent to the atmosphere.

Tidal volumes of 800 to 1000 ml, rates of 10 to 12 breaths/min, and inspiratory flow rates of 30 l/min are recommended for adults.

The risk of gastric inflation and regurgitation can be minimized by avoiding high inflation pressures, allowing full expiration to occur, and having an assistant apply cricoid pressure if necessary.

Although expired air resuscitation is an acceptable practice for the non-medical bystander, ventilation using a self-inflating bag and mask is more effective. Bag-and-mask systems comprise a self-inflating bag with an inlet valve at one end to entrain air-oxygen mixtures and a one-way patient valve at the other. This has a 15-mm connector which allows connection to a mask, endotracheal adaptor, endotracheal tube, laryngeal mask, or tracheostomy. At oxygen flow rates of 5 l/min through the inlet valve, concentrations of 40 to 50 per cent oxygen can be obtained. If higher inspired oxygen concentrations are needed, a reservoir bag can be attached to the inlet and oxygen flow rates of 8 to 10 l/min selected. When the reservoir bag is not used, caution is recommended at oxygen flow rates in excess of 5 l/min because overfilling of the self-inflating bag can occur causing the patient valve to stick in the inspiratory position. This allows expired air to re-enter the bag with consequent rebreathing of carbon dioxide. Positive end-expiratory pressure valves can be connected to the patient valve if necessary. During ventilation with this system, inspiratory-expiratory time (I:E) ratios of 1:3 are recommended with respiratory rates and chest excursion appropriate for patient size and age ( B§s.keitJ..98..9.).

An alternative to bag-and-mask ventilation is the insertion of a laryngeal mask airway. Since its introduction ( Brain 1983), the laryngeal mask airway has been used extensively and has proved easy and quick to insert. Ventilation of the lungs is reliably achieved, although controversy exists about the degree of protection against regurgitation. It can be invaluable in the intensive care unit (ICU) as an intermediate step between intubation and unsupported spontaneous breathing ( AEosio §.D.d Conci 1995).

Sleep Apnea

Sleep Apnea

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